Asymmetrical sail fabric

ABSTRACT

A sailcloth in roll good form permits efficient and cost effective construction of cross cut and vertical cut, laminate sails based on “off-angle,” (asymmetrical) load bearing fibers. The sailcloth also may include a conventional warp and fill thread or fiber layout. Such sailcloth illustratively is significantly less susceptible to load force stretch, creep elongation, and airfoil shape deformation because, among other things, it is not dependent on the load bearing limitations of symmetrical, woven or knitted roll good sailcloth.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.10/922,237, entitled “Asymmetrical Sail Fabric,” filed Aug. 19, 2004 nowU.S. Pat. No. 7,104,210, which in turn claims priority from U.S.provisional patent application Ser. No. 60/496,338, entitled“Asymmetrical Sail Fabric,” filed Aug. 19, 2003. Each of theabove-described applications is hereby incorporated by reference, in itsentirety.

FIELD OF THE INVENTION

The invention generally relates to sailcloth and, more particularly, theinvention relates to roll good sailcloth.

BACKGROUND OF THE INVENTION

Maintenance of the airfoil shape of a sail is critical to itsperformance. Conventional woven, knit, or scrim sailcloth, whether ofnatural fibers or the latest polyester, nylon, aramid, PEN, PBO, ultrahigh molecular weight polyethylene (UHMWP), or carbon fiber, is prone tostretch, creep elongation, and airfoil shape deformation because ofnon-linear forces on the sailcloth under load, particularly when sailingupwind. When sailcloth is stretched and deformed, the airfoil shape ofthe sail is deformed, and the lifting capability of the airfoil isdegraded. Since the mid 1970s, a number of load force advances have beenmade in the design of sails, in the use of different materials, and inmethods of constructing sails, all intended to limit stretch, creep,elongation, and deformation of sailcloth and sails. These advances rangefrom ever more tightly woven fabrics, development of more resilientfibers, alternative designs for sail panels, computer aided analysis ofload forces, and computer aided design and manufacture of integrallyinterconnected sailcloth panels for individual sails, computer aideddesign of the direction of the thread or fiber layout of each panel ofindividual sails, and computer aided, three dimensional “molding” ofindividual sails.

Flat, or working sails, are those sails used to propel a sailing vesselas close as possible into the wind, tacking, or at wider angles acrossthe wind, reaching. Sails in this category include mainsails, jibs,Genoas, and a variety of other sails that usually have at least one edgeattached to a mast, boom, or wire running from a spar to the vessel. Inthis realm of working sails are two categories of sailcloth that can bedefined as woven and laminated cloth.

Woven Sailcloth & Cross-Cut Panel Layouts

Woven sailcloth is typically made with continuous filament polyester,such as Dacron, on looms that permit very dense constructions. Thisstyle of cloth is created by an over-then-under intersection of warp(fibers running the length of the roll) and weft (fibers running acrossthe width of the roll) yarns that are tightly packed together. Byvarying the size, or denier, of these fibers in conjunction with thefiber count in either direction, the stretch properties of the cloth maybe altered to better suit a particular sail design. For example, bycombining a relatively large weft yarn with a small warp yarn, all thecrimp displacement can be allocated to the warp yarn, in effect, theloom is bending the warps around the weft fibers that are being heldstraight. The result is a low stretch fabric in the weft direction withthe warp direction easier to stretch as the added length of crimp getspulled out of the fiber with loading.

With the exception of some experiments using tri-axial weaves which weresymmetrical about the warp and the 45° axis, conventional wovensailcloth has been based upon a symmetric warp—weft fiber orientation of0° for the warp and 90° for the weft. These fabrics are most commonlyarranged in cross-cut panel configurations to align the stronger weftfibers up the leech of the sail in the general direction of the loadingout of the head and clew corners of the sail. For the loads notfollowing this path, the stability of the woven cloth generated by thevery tight weave and resin finish helps reduce off thread-line stretchand promotes recovery from any cloth elongation that does occur. Whilesome woven sail fabrics are designed to be used in radial constructions,the vast majority of sails made from woven Dacron are designed withcross-cut panel layouts. Because the woven cloth is typicallysymmetrical about the warp axis or machine direction, the fabric can berolled either way in the panel, leech to luff or luff to leach, andstill maintain the desired alignment of the weft fibers to the loads.However, the symmetry of the woven cloth can also be inefficient, sincevarious fibers in the cloth may not be aligned to a load.

An exemplary cross-cut sail 100 is illustrated in FIG. 1( a). The fabriclayout in an exemplary panel 102 of the cross-cut sail is illustrated inFIG. 1( b). Cross-cut sail constructions can vary in some details butthe general panel layout has the seams of the cloth running from theleech of the sail to the luff at an angle roughly perpendicular to astraight line from the clew to the head of the sail. In so doing, theweft threads 106, which are usually lower in stretch than the warpfibers 104 in a cross-cut panel, are aligned with the strongest loads inthe sail. Cross-cut panels 102 are generally rectangular in shape withone edge cut at an angle where it affixes to the mast. The cross-cutpanels 102 are joined along their long edges which are slightly curvedby the sailmaker to provide the necessary 3-dimensional shaping in thefinished sail to generate lift.

Because the panels are generally rectangular, they can be cut from rollsof woven fabric with relatively little wasted material. The full widthof the cloth can be utilized and with careful nesting of the panels toalign the short edges together, it is not uncommon to achieve fabricutilization of 90-95%, meaning, for example, the sailmaker will need toorder 55 yards of fabric for a sail that will ultimately use 50 yards ofmaterial.

Laminated Sailcloth and Tri-Radial Layouts

In the early 1980's, higher modulus fibers like Kevlar were introducedto sailcloth manufacturers. With considerable more strength and lowerstretch than polyester Dacron fibers, Kevlar was first trialed in highperformance sails for the America's Cup. Prone to flex fatigue andhaving no shrinkage even with high temperatures, this new fiber did notlend itself to the traditional tightly woven constructions used withDacron and further tightened up with shrinkage through heat-setting.

Rather, this new fiber was woven into more loosely designedconstructions that were stabilized with the addition of a Mylar film. Bylaminating a sheet of 2 or 3 mil film to these Kevlar taffetas, thecloth manufacturers imparted enough stability to the weaves to resistthe off-thread line loading and allow the sails to hold their designedshapes. Early trials were plagued with failures in lamination and actualcloth breakage but improvements in lamination techniques and a betterunderstanding of fiber content to strength requirements has all buteliminated those problems.

Concurrent to the advent of laminated cloth was the development of thetri-radial panel construction, first used in sails for the America'sCup. An exemplary tri-radial sail 201 is shown in FIG. 2( a), while thefabric layout of an exemplary panel 202 is shown in FIG. 2( b). Thisconstruction technique allows the sailmaker to align the warp threadline 204 of the cloth in the general direction of the loads emanatingout of the sail corners. Hand in hand with this trend, cloth suppliersstarted to make warp oriented laminates where the majority of thefabric's strength was in the warp tread 204 direction and not in thedirection of the weft threads 206. Because laminators can keep a highrate or tension on the warp fibers during manufacture, the stretchresistance of the warp could be optimized to limit fabric elongation tolevels not possible in woven cloth. This new construction techniquecombined with the use of high modulus fibers in warp oriented laminatesresulted in a new level of performance in terms of strength to weightand shape retention.

However, tri-radial design and panel configurations increases the laborrequired to build a sail and the amount of cloth needed to make all thepanels. Because radial panels 202, or gores, are generally triangular inshape, they are not as efficiently nested into the sail as is across-cut panel. Furthermore, to maintain thread lines in the gores,even with tight panel nesting, a higher percentage of sail fabric iswasted when compared to the cloth utilization with cross-cut panels.Average cloth utilization rates for common tri-radial panel designs arein the 80% range meaning a sailmaker will need to use almost 63 yards offabric for the same sail that used 55 yards in the cross-cut designexample. Compounding added expense of poor cloth utilization in thetri-radial design is the increased labor required for the assembly ofthe many more panels than needed for the same sail build as a cross-cutdesign.

For grand prix racing, where price is not a paramount concern to thesail maker or the sailor and where conventional roll good sailcloth isno longer widely used, some advances have been very successful. Theseinclude Peter G. Conrad's “airframe” patent, U.S. Pat. No. 4,593,639,and his “Genesis” patent, U.S. Pat. No. 4,708,080, which constructs asail “without sailcloth”; and Jeanne-Pierre Baudet's molded saidconstruction methods, U.S. Pat. No. 5,097,784, U.S. Pat. No. 6,112,689(used in North Sails' highly regarded 3DL® sails). Other patents, suchas Fred Aivars Keir's woven laminate patent, U.S. Pat. No. 6,311,633,may also advance grand prix sailmaking. However, the cost of fabricationand technology required for these advances is beyond the resources ofmost sail makers and similarly beyond the budgets of most amateursailors, even serious recreational racing and offshore cruising sailors.

It therefore is desirable for a sailcloth to be both affordable and lesssusceptible to load force stretch creep elongation, and airfoil shapedeformation.

SUMMARY OF THE INVENTION

In accordance with various embodiments of the invention, a sailcloth inroll good form permits efficient and cost effective construction ofcross cut and vertical cut, laminate sails based on “off-angle,” loadbearing fibers. The sailcloth may also include a conventional warp andfill thread or fiber layout. Such sailcloth illustratively issignificantly less susceptible to load force stretch, creep elongation,and airfoil shape deformation because, among other things, it is notdependent on the warp (0°) and fill (90°) load bearing limitations ofconventionally woven, knitted, or formed scrim roll good sailcloth.

As noted above, this affordable sailcloth may be produced as roll goodsailcloth in a broad variety of fabrics, and it can be used readily andefficiently by sail makers with existing design, cutting, and bondingtechnology to produce crosscut or vertical cut sails. Moreover,embodiments of this invention also eliminate the labor intensive,expensive, and wasteful methods and techniques of radial cut sailmaking, which have been devised as one common approach to load forcedesign.

In accordance with various aspects of the invention, a sail cloth and amethod of making a sail cloth in roll good form are presented. The sailcloth has a machine that runs the length of the sail cloth. The sailcloth includes at least three layers of fiber that are overlaid. Eachlayer of fiber is formed from a plurality of substantially parallelfibers generally oriented in a direction that is different than thefibers in any other layer. The layers of overlaid fiber form anasymmetric pattern across the machine axis.

In accordance with another aspect of the invention, a sail cloth and amethod of making a sail cloth in roll good form is presented, the sailcloth having a first face and a second face. The sail cloth includesthree or more non-woven overlaid layers of fiber. The layers of fiberinclude a first layer of fiber having fibers arrayed in parallel andoriented in a first direction. A second layer of fiber having fibers isarrayed in parallel and oriented in a second direction different fromthe first direction. A third layer of fiber having fibers is arrayed inparallel and oriented in a third direction different from the firstdirection and the second direction. The overlaid layers of fiber form apattern that when viewed from the first face is different from whenviewed from the second face.

In embodiments related to the above-describe embodiments, the at leastthree layers of fiber are non-woven. One of the at least three layersmay have fibers oriented parallel or perpendicular to the machine axis.The at least three layers of fiber may be combined with one or moresubstrates to form the cloth. The at least three layers of fiber may belaminated together using, for example, a material chosen from the groupof materials consisting of a polyester film and a taffeta. The at leastthree layers of fiber may be molded together using a mold material, suchas a polymer.

In further embodiments related to the above-described embodiments, theat least three layers of fibers may vary or have equal denier and/ordenier per inch. All the layers of fiber that form the sail cloth form,when overlaid, may form a pattern that lacks lack mirror image symmetryacross the machine axis. The at least three layers of fiber may includefour layers of fiber.

In still further embodiments related to the above-described embodiments,a sail is formed from the sail cloth. The sail may include a pluralityof cross-cut panels, wherein at least one of the cross-cut panelsincludes the sail cloth. The sail may include a plurality of radialand/or vertical-cut panels, wherein at least one of the radial and/orvertical-cut panels includes the sail cloth. The sail may be a headsail,a mainsail, or a spinnaker. Each layer of fiber may be aligned along apredetermined load line on the sail during expected sailing conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and advantages of the invention will be appreciated morefully from the following further description thereof with reference tothe accompanying drawings wherein:

FIG. 1( a) schematically shows a cross-cut sail (prior art);

FIG. 1( b) schematically shows the woven layers of fiber within anexemplary panel of the cross-cut sail of FIG. 1( a).

FIG. 2( a) schematically shows a radial cut sail (prior art);

FIG. 2( b) schematically shows the woven layers of fiber within anexemplary panel of the radial cut sail of FIG. 2( a).

FIG. 3( a) schematically shows an exemplary cross cut panel arrangementfor a sail using roll good sailcloth, in accordance with an embodimentof the invention.

FIG. 3( b) schematically shows the layers of fiber within the roll goodsail cloth of FIG. 3( a), in accordance with an embodiment of theinvention.

FIG. 4( a) schematically shows an exemplary sail having cross cut panelsperpendicular to the mast, in accordance with an embodiment of theinvention.

FIG. 4( b) schematically shows in more detail the layers of fiber withinthe roll good sail cloth of FIG. 4( a), in accordance with an embodimentof the invention.

FIG. 5( a) schematically shows an exemplary cross cut panel arrangementfor a sail using roll good sailcloth incorporating fiber layers at 70,82, and 90 degrees from the warp/machine axis, in accordance with anembodiment of the invention.

FIG. 5( b) schematically shows the 70 degree fibers of the sail of FIG.5( a).

FIG. 5( c) schematically shows the 82 degree fibers of the sail of FIG.5( a).

FIG. 5( d) schematically shows the 90 degree fibers of the sail of FIG.5( a).

FIG. 6( a) schematically shows an exemplary leech or vertical-cut panelarrangement for a sail using roll good cloth, in accordance with anembodiment of the invention.

FIG. 6( b) schematically shows the layers of fiber within the roll goodsail cloth of FIG. 3( a), in accordance with an embodiment of theinvention.

FIG. 7 shows a process of making a roll-good sail cloth in accordancewith an embodiment of the invention.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Various embodiments of the invention advance warp and fill technology inthe area of roll good sailcloth and are intended to provide sailclothand sails that resist airfoil shape deformation in a manner that islargely comparable to grand prix sails, but which are significantly lessexpensive to design and manufacture. This technology also provides rollgood sailcloth that is largely comparable in weight and durability tothe materials used to manufacture grand prix sails. Moreover, thistechnology can be applied to the latest polyester, nylon, aramid, PEN,PBO, UHMWP, or carbon fabrics. Significantly, embodiments of the presentinvention minimize (in some cases, eliminate) significant capitalinvestment by sail makers and dispense with expensive radial cutting.

It has now been found that non-woven, laminated roll good sailcloth canbe produced with multiple, load bearing fiber layers arrayed inasymmetrical, “off-angle” axes, as well as in or together withconventional warp and fill layout. In making the sail, the roll goodsail cloth (which typically is manufactured along a machine axis to acertain length and sold as a roll of cloth) is cut into panels based ondesired features and implementation of the design, usually by use of acomputer program. Due to the asymmetric pattern of the fibers within thepanel, the fibers within the panels of the sail can be generally alignedwith expected loads under sailing conditions, without the added weightof having additional, non-load bearing symmetrical fibers.

In illustrative embodiments of the invention, an assembly of multiplefiber layers are arrayed at various angles off a conventional warp(fibers that run the length of the sail cloth) or fill direction (thefill direction is also referred to as the weft, these are fibers thatconventionally run across the width of a the sail cloth—perpendicular tothe warp) such that the fiber orientation of the roll good cloth isasymmetrical across the machine axis that runs the length of the sailcloth. The multiple fiber layers forming the sailcloth lack mirror imagesymmetry across the machine axis. Furthermore, the fibers forming thesail, which form a first face and a second face, form a pattern thatwhen viewed from the first face is different from when viewed from thesecond face. Each fiber layer is arrayed in its own plane so crimpdeformation is eliminated. In addition to being non-woven, the layers offiber may not require any additional knits or strands to hold thevarious layers of fiber together.

The symmetrically arrayed fiber layers produced in accordance withvarious embodiments of the invention may be laminated to a film surfaceto complete the material. The laminate may include materials such asMYLAR polyester film with a uniform adhesive such as ADCOTE 122.Alternative laminate surfaces can be used, such as polyester or taffeta,or other films such as Tedlar. In other embodiments, the layers of fibermay be molded together using a mold material such as a polymer.

As with sand prix sails, the fibers, arrayed in accordance with aspectsof the invention, are the primary load bearing structure of the sail. Inpreferred embodiments of the invention, the sail includes at least threelayers of fiber to form a durable, stable sail that can withstand avariable number of loads seen in a particular sailing environment. Incontrast to grand prix sails, however, aspects of the invention permitefficient, relatively inexpensive design and construction of roll goodsailcloth sails, oriented to expected loads and resistant to airfoilshape deformation.

To illustrate these concepts, FIG. 3( a) shows an exemplary cross cutpanel arrangement for a mainsail 300 using roll good sailcloth thatincorporates the fiber arrays shown in FIG. 3( b), in accordance with anembodiment of the invention. Using the non woven method of variousembodiments of the invention, load bearing fiber layers can be laid outin each panel 303 at angles off the conventional warp/fillperpendicular, as illustrated. As shown in FIG. 3( b), the warp fiber305 and fill fiber 307 may be, for example, arrayed at right angles,while off angle fibers 308, 309, and 310 may be arrayed at variousangles from the fill, such as, without limitation, 10 degrees, 20degrees and 35 degrees from the fill respectively.

Of course, other angles may suffice. Specifically, the angles of thefibers may be varied infinitely to suit the sail maker's purpose. Inpractice, a pre-defined range of fiber angles should be sufficient forcrosscut or vertical cut design and manufacture of most sails. Thefibers in each warp, fill, and off-angle fiber layer are arrayed inparallel to the fibers of that layer. In each case also, the denier ofthe fiber and denier per inch of each layer of fiber can be variedinfinitely to suit design and sail use requirements. For example, anocean passage offshore sail typically has a higher denier and denier perinch than the sail for an inshore racing sailboat. Again, in practice, adefined range of fiber characteristics should be sufficient for a widevariety of sail uses.

As noted above, embodiments of the present invention permit efficient,cost effective design and manufacture of sails using cross cut orvertical cut sail design. For example, a mainsail or headsail 401 havingcross cut panels 402 designed to be perpendicular to the mast, as shownin FIG. 4( a) may include an asymmetrical fiber array shown in FIG. 4(b). Using the asymmetrical method as noted herein, load bearing fiberlayers can be laid out at angles off the conventional warp/fillperpendicular. It is not necessary to rotate panels or to design, cut,and fasten many panels (as required by radical cut designs forconventional roll good sailcloth). Panels can be cut and oriented to thevertical angle of the luff in the case of a mainsail or the verticalangle of the mast in the case of a jib or genoa headsail. Theasymmetrical load bearing fiber layers in the sailcloth may be orientedwithout rotation or special cutting to absorb load on the vertical, atoff angles from the vertical, and, of course, at 90 degrees. In variousembodiments, load lines on the sail during expected sailing conditionsmay be predetermined, with each layer of fiber aligned along one of theload lines. Embodiments of the invention may produce sailcloth so thatthe leech loads are off the angle of conventional fill and aligned to amore acute angle. The thread line layout in FIG. 4( b) may beadvantageously designed for this configuration. Instead of fill fibersat 90 degrees to the warp, exemplary fiber layers 406, 407, and 408 arelaid at approximately 45, and 80 degrees, respectively, in line withloads out of the clew. This allows for excellent cloth utilization, easyconstruction, and if required, battens in the seams.

To illustrate more clearly the various layers of fiber, FIG. 5( a) showsa cross cut sail 501. The cross cut sail 501 includes panels that areformed from a sail cloth with the following layers of fiber: a layer offiber oriented along the warp/machine axis (not shown); a layer of fiber502 at 70 degrees to the warp/machine axis as shown in FIG. 5( b); alayer of fiber 504 at 82 degrees to the warp/machine axis as shown inFIG. 5( c); and a layer of fiber 306 at 90 degrees to the machine axisas shown in FIG. 5( d), in accordance with an embodiment of theinvention. Each of these fiber layers 502, 504 and 506, and the layer offiber along the machine axis are overlaid to form the sailcloth.

FIG. 6( a) represents a leech or vertical-cut sail 602 incorporatingillustrative embodiments of the invention, where the panels 603 arealigned with the warp parallel to the leech straight line. As shown inFIG. 6( b), the warp fibers 604 and fibers off angle to the warp 605become the structural members in the sail. FIGS. 6( a-b) illustrate thedesign flexibility of roll good sailcloth incorporating aspects of theinvention. Vertical cut sails may be particularly suited to certainroller furling systems, and vertical cut designs may offer creative loadforce design options to sail makers relative to both cross cut andradial cut designs.

In accordance with various embodiments of the invention, duringmanufacturing the warp, fill (if required), and off angle fibers may be,without limitation, laid out on a frame by way of a computer drivenfiber laying head. Fiber angles and density are determined by thesailcloth designer and entered into a standard computer aidedmanufacturing (“CAM”) program for the fiber-laying machine. Once laidout on the frame, the fibers are then incorporated within a laminate.For example, the fiber layers may be incorporated between two pieces offilm to form a laminate.

FIG. 7 shows a process of making a roll good sail cloth in accordancewith an embodiment of the invention. The process begins at step 701, inwhich three or more layer of fiber are overlaid. As in above-describedembodiments, each layer of fiber is formed from a plurality ofsubstantially parallel fibers generally oriented in a direction that isdifferent than the fibers in any other layer. Furthermore, all thelayers of fiber that form the sail cloth form, when overlaid, a patternthat is asymmetric along the machine axis.

The process then continues to step 703, in which the multiple layers offibers are hot-nipped onto a film coated with a heat-sealable adhesivesuch as Adcote 1217D at a temperature of 300° F. The fibers are thusglued in their desired orientation to the film in what amounts to afirst pass lamination step. Thus, no knitting of the fibers is required.This first pass film may be Mylar, a Mylar bonded to polyester taffeta,or any one of several other films.

The fibers and film are then run through a laminator for the finalbonding process, in step 705. One or both sides of the cloth may belaminated with one or more layers of film to form the roll good sailcloth.

Although various exemplary embodiments of the invention have beendisclosed, it should be apparent to those skilled in the art thatvarious changes and modifications can be made which will achieve some ofthe advantages of the invention without departing from the true scope ofthe invention. These and other obvious modifications are intended to becovered by the appended claims.

1. A sail cloth in roll good form, the sail cloth having a machine axisthat runs the length of the sail cloth, the sail cloth comprising: atleast three layers of fiber, the at least three layers being overlaid,each layer of fiber formed from a plurality of substantially parallelfibers generally oriented in a direction that is different than thefibers in any other layer, wherein all the layers of fiber that form thesail cloth form, when overlaid, an asymmetric pattern across the machineaxis.
 2. The sail cloth according to claim 1, wherein the at least threelayers of fiber are non-woven.
 3. The sail cloth according to claim 1,wherein all the layers of fiber that form the sail cloth form, whenoverlaid, a pattern that lacks lack mirror image symmetry across themachine axis.
 4. A sail comprising the sail cloth of claim
 1. 5. Thesail according to claim 4, wherein the sail has predetermined load linesduring expected sailing conditions, and wherein each layer of fiber isaligned in a direction along one of the predetermined load lines.
 6. Amethod of making a sail cloth in roll good form, the salt cloth having amachine axis that runs the length of the sail cloth, the methodcomprising: overlaying three or more layers of fiber, each layer offiber being formed from a plurality of substantially parallel fibersgenerally oriented in a direction that is different than the fibers inany other layer, wherein all the layers of fiber that form the sailcloth form, when overlaid, a pattern that is asymmetric along themachine axis.
 7. The method according to claim 6, wherein all theoverlaid layers that form the sail cloth form a pattern that lacksmirror symmetry along the machine axis.
 8. The method according to claim6, wherein the three or more layers of fiber are non-woven.
 9. Themethod according to claim 6, wherein the sail cloth is to be included ina sail, the method further comprising: determining load lines on thesail during sailing conditions; and aligning each layer of fiber alongone of the load lines.
 10. The method according to claim 6, furthercomprising hot-nipping the three or more layers of fiber onto a filmcoated with a heat-sealable adhesive.
 11. The method according to claim10, wherein the adhesive is Adcote 1217D.
 12. The method according toclaim 10, further comprising laminating the hot-nipped layers of film.13. The method of making a non-woven sail cloth in roll good form, thesail cloth having a first face and second face, the method comprising:overlaying three or more layers of non-woven fiber such that all thelayers of fiber that form the sail cloth form, when overlaid, a patternthat when viewed from the first face is different from when viewed fromthe second face, wherein overlaying the three or more layers ofnon-woven fiber includes: arraying a first layer of fiber in parallel ina first direction; arraying a second layer of fiber in parallel in asecond direction different from the first direction; and arraying athird layer of fiber in parallel in a third direction different from thefirst direction and the second direction.
 14. The method according toclaim 13, wherein the overlaid layers lack mirror symmetry along themachine axis.
 15. The method according to claim 13, further comprisinghot-nipping the three or more layers of fiber onto a film coated with aheat-sealable adhesive.
 16. The method according to claim 15, whereinthe adhesive is Adcote 1217D.
 17. The method according to claim 15,further comprising laminating the hot-nipped layers of film.
 18. Themethod according to claim 13, wherein the said cloth is to be includedin a sail, the method further comprising: determining load lines on thesail during sailing conditions; and aligning each layer of fiber alongone of the load lines.
 19. The product formed by the process of claim13.
 20. The method according to claim 13, further comprising laminatingthe three or more layers at fiber together.